Getting a pivotchart in a subform to update from a combobox on the main form

[jak26]

Hi

I have a pivot chart in a subform that is run from a query.

On the main form I have a combobox that is supposed to change one criteria in the query and update the pivot chart however this seems to be a lot easier said than done


I had:
Forms![frm_monthly_graphs]![Combo19].[Value]
in the criteria field of the query but this does not work